Description: (Adapted from the application) The objectives of the Animal Physiology Core are 1) to perform studies of insulin action, glucose homeostasis, and body composition on mouse or rat models created by or obtained by investigators who are members of the Center; 2) to teach investigators how to carry out in vivo studies of insulin action, glucose homeostasis and body composition, and in vitro studies of insulin signaling, glucose transport and metabolism, and fatty acid oxidation and storage; and 3) to provide consultation to investigators in designing studies of insulin action, glucose homeostasis, and the impact of altered body composition on insulin action. Services of the Core will include carrying out studies of insulin responsiveness by euglycemic clamp, and assessing oxygen consumption and body composition. The Core will also teach investigators methods of adipocyte isolation and of dissection and incubation of isolated skeletal muscles to study glucose transport, insulin signaling, and glucose and fatty acid metabolism. In addition, the Core will teach investigators to perform in vivo studies such as insulin tolerance tests and glucose tolerance tests, and Core personnel will provide ongoing consultation on study design for both in vivo and in vitro studies. The Core will also provide several specialized pieces of equipment such as an Oxymax machine for determination of oxygen consumption, a DEXA scanner for noninvasive analysis of body composition, and a Coulter Counter for counting adipocytes. The Core Director, Dr. Barbara B. Kahn, has extensive experience with the in vivo and in vitro assays offered by the Core and is currently using these assays for the characterization of new transgenic mouse models of insulin resistance and diabetes.